1. Field of the Invention
This invention relates to a device for diluting liquid sample.
2. Description of the Prior Art
In biochemical analyzing devices, such as a device for analyzing ionic concentrations or various ingredients of liquid samples such as serum, the liquid sample is generally diluted at a predetermined rate of dilution before effecting the analysis. As a means for diluting the liquid sample, it has been proposed to use two roller pumps, so that the liquid sample and the diluent solution are sucked by the roller pumps at given rates, respectively, so as to mix the thus sucked liquid sample and the diluent solution and to feed the mixture to a flow-cell or reaction vessel at a predetermined position. The device for diluting liquid sample of the prior art, however, uses a fixed ratio of revolving speeds for the two roller pumps, and the rate of dilution is determined by a ratio of diameters of tubes constituting the roller pumps. Thus, the device of the prior art has shortcomings in that the rate of dilution cannot be selected at will and that, if the rate of dilution is unintentionally changed by replacement of a worn-out tube with a new tube, correction for such change is extremely difficult.